In blow molding apparatus of the wheel type, a plurality of sets of molds are provided in circumferentially spaced relation on a wheel or plate that is rotated about a horizontal axis. As the wheel plate is rotated, the mold sections are moved toward and away from one another to enclose a tube that is extruded by an extruder between the open molds, close the molds and blow the enclosed portion of the tube into a hollow article such as a container. One of the problems with respect to such an apparatus is that the extruder must be positioned so that the extrusion head properly aligns the plastic tube or parison that is being extruded with respect to the plane of juncture and centerline of the molds. Such an adjustment is necessary when the molds are changed to a different size. Heretofore this has been achieved by moving the extruder bodily with respect to a base. In one type of mechanism, the base is movable vertically and horizontally toward and away from the molding apparatus. However, the movement of an extruder horizontally requires substantial effort and makes the adjustment difficult and costly.
As a result, it has been common to provide retractable wheels on the molding apparatus so that, when it is desired to change the relationship of the extruder head radially of the apparatus, the wheels are lowered and the apparatus is physically moved. This is obviously difficult, time consuming and costly and, in addition, necessitates stopping the operation of the machine.
Accordingly, among the objectives of the present invention are to provide an apparatus wherein the relationship of the extruder head radially with respect to the molds on the blow molding apparatus can be readily achieved quickly and efficiently, at relatively low cost and while the machine is operating.
In accordance with the invention, the extruder is mounted on a platen which is pivoted to a base plate for movement about a vertical axis such that an extruder mounted on the base plate and having an extrusion head can be adjusted radially of the wheel to align the extruded plastic material with the plane of juncture of the mold sections.